1. Field of the Invention
The present invention relates to a printing system, and more particularly concerns a printing system which can continuously print a cover portion and a body portion.
2. Description of the Background Art
In recent years, in the printing industry, printing machines of a type referred to as a digital printing machine or an on-demand printing machine have been widely used. The digital printing machine is a printing machine which can directly carry out a printing process based upon electronic printing data that has been formed by a conventional Desk Top Publishing (DTP) process. More efficient and labor-saving printing processes have been achieved by introducing such a digital printing machine capable of directly carrying out a printing process based upon electronic printing data to printing processes.
Moreover, in a recently developed technique, with a bookbinding machine being directly connected to a digital printing machine, bending and bookbinding processes are carried out on printed sheets that have been subjected to a printing process by the digital printing machine so that processes up to formation of a booklet are executed more efficiently.
However, even when the automatic binding machine is directly connected to a digital printing machine, it is not easy to form a booklet by using the digital printing machine.
For example, in the case of glued-on cover bookbinding (a booklet in which the front cover and the rear cover are printed on one printing sheet with these being laid on the printing sheet, and the bookbinding is made in a manner so as to wrap the body portion with the sheet), a booklet is constituted by a cover portion consisting of a sheet of paper on which the front cover and the rear cover have been printed and a body portion having a plurality of sheets of paper that forms a booklet main body. When a bookbinding operation of this type is carried out, a printing process for a cover portion and a printing process for a body portion need to be carried out. In the case of a conventional printing process, since the printing processes of the cover portion and the body portion are carried out in respectively independent processes, no problems are raised when a booklet is formed finally through a bookbinding process.
However, in the conventional digital printing machine, since printing data for printing a cover portion and printing data for printing a body portion are managed in a separate manner, the cover portion and the body portion need to be printed in a separated manner. For this reason, even when the automatic bookbinding machine is directly connected to the digital printing machine, sheets of printed paper corresponding to the cover portion and the body portion are not continuously supplied to the automatic binding machine.
Here, although a booklet sometimes needs a back cover, the conventional digital printing machine fails to satisfy this demand.
Moreover, since printing data for printing the cover portion has to formed prior to the printing and bookbinding processes, it is not possible to form booklets in a flexible manner.